When we describe something as happening "in full force", we typically mean that it is occurring with great energy, strength, and intensity. There are several synonyms that we can use to convey a similar meaning, depending on the context and the tone we want to convey. Some possible options include "full throttle", "at full tilt", "with full vigor", "with full power", "with full intensity", and "with maximum force". Each of these phrases can drive home the idea that something is happening with great momentum and impact, whether we are talking about a storm, a protest, an argument, or a sales campaign.